Out of the two Aeterna, the second is Nox. He is the opposite of Lux, he is pure darkness. A being of falsehood and pain. Nox often appears to the viewer as the embodiment of their greatest fear.

Nox is barely mentioned in the entire run of Master defenders and only seen by few. Many of those who are still sane enough to recount the experience, even in the slightest suffered from amnesia at least ones or twice.